Nepal Journal of Biotechnology
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Isolation of Polyhydroxybutyrate (PHB) Producing Bacteria, Optimization of Culture Conditions for PHB production, Extraction and Characterization of PHB
Full text linkPolyhydroxybutyrates (PHBs) are energy reserves synthesized by different micro-organisms such as Alcaligenes, Pseudomonas, Staphylococcus, Algae, in excess of carbon and limitation of nutrients like nitrogen. These biopolymers are suitable alternate to synthetic carbon-based polymers. However, the high production cost limits their commercialization. The aim of this study was thus, focused on optimization of culture condition for maximum PHB production in an attempt to reduce the production cost. The micro-organisms for this purpose were isolated from 4 different soil samples and screened for PHB production. Culture conditions for these organisms were optimized by changing the parameters, viz., incubation time, pH, carbon source and NaCl concentration. Thus, optimized culture condition was used to culture the isolates for extraction of PHB and its analysis. The extracted compounds on FTIR-analysis gave characteristic C=O peak of PHB, thus, confirming the seven isolates to be PHB producers. Results for optimized parameters for the isolated PHB positive species showed that synthesis of PHB was maximum at 48 hours i.e. during the early stages of stationary phase. However, different isolates favored different culture conditions. Highest PHB accumulation and growth of isolates were seen at pH 7 and 9. Similarly, it was observed that glucose was favored by 4 isolates and sucrose was favored by 3 isolates. Interestingly, NaCl concentration did not cause significant effect on neither the bacterial growth nor the PHB production. During the extraction of PHB from the optimized culture conditions, extraction of PHB from broth gave significant yield than that from agar. A good PHB yield from broth amounting to 36.41% and 34.59% was observed for Bacillus pasteurii and Micrococcus luteus respectively, showing a potential for their exploitation in industrial PHB production. At optimized conditions, 7 isolates exhibited significant PHB yields, thus showing a potential for further exploitation
Screening of Methicillin Resistant Staphylococcus aureus (MRSA) from Wounds in Pediatric Patients Visiting Tertiary Care in Hospital
Full text linkThe extent of methicillin-resistant Staphylococcus aureus (MRSA) in children is still unknown. The collected wound pus samples were processed. Identification of S. aureus was done according to standard microbiological procedures as per the clinical laboratory standards institute (CLSI) guidelines (2016). The antibiogram of the isolates was carried out by the Kirby-Bauer disc diffusion technique. MRSA was determined by measuring the zone of inhibition (ZOI) surrounding to cefoxitin disc, with resistance defined as ZOI of ≤ 21 mm. Out of 357 bacterial culture-positive samples, 278 (77.87 %) were S. aureus isolates, among them 102 (36.69%) were found to be MRSA. The percentage of MRSA isolates was found high in male children and inpatients with 61.76 % and 73.52% respectively. All the MRSA isolates were susceptible to gentamicin (79.41%), whereas (91.17%) were resistant to penicillin. The distribution of MRSA in inpatients 75 (73.52%) is higher than that of outpatients 27 (26.74%). This study shows that the MRSA occurrence is prevalent in pediatric patients
Antibiotic Susceptibility Profile of respiratory pathogens obtained at tertiary care hospital from western Nepal
Full text linkThe prevalence and drug resistance of the respiratory pathogens is increasing gradually in Nepal. However, their detail study is rare in the western region of Nepal. Hence, this study was carried out to know the incidence and antibiotic susceptibility profile of the respiratory pathogens obtained at a tertiary care center located at Pokhara. 139 pathogens were isolated from 460 clinical samples included. Significant pathogens were Gram-negative bacteria 94 (67.62%), followed by 28 (20.15%) Candida, and Gram-positive isolates 17 (12.23%). The growth rate was significantly higher for sputum samples in comparison to throat swabs. Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter were significant Gram-negative isolates while Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus pyogenes were Gram-positive pathogens. Sensitivity rate was higher for colistin and imipenem among Gram-negative isolates while lower sensitivity was for cefepime. Vancomycin was effective against all tested Gram-positive isolates while erythromycin and ciprofloxacin were less effective
Pharmacological In vivo test to evaluate the antidepressant activity of polyherbal formulation
Full text linkThe antidepressant effects of the polyherbal formulation (PF) (contain four extracts of medicinal plants namely: Nyctanthes arbortristis, Hippophae salcifolia, Ocimum tenuiflorum and Withania somnifera ) was examined by evaluating the extent of reduction of behavioural alterations and neurotransmitter in the rats stressed by forced swim test (FST). In the present study, compared with the model control group (FST), the altered behavioural parameters were attenuated significantly (P < 0.05) in the group treated with the PF (100, 200 and 400 mg•kg−1), comparable with the standard drug treated group, Sertraline (10mg•kg−1). The PF and Sertraline significantly (P < 0.05) increased the level of the neurotransmitter such as serotonin, dopamine, acetylcholine and noradrenalin whereas decreased the level of monoamine oxidase along with oxidant in the brain of the stressed rats. PF and Sertraline were also involved in the reduced oxidant and generated antioxidant in the stressed rats. The results indicated that polyherbal formulation exhibited significant antidepressant activity, as indicated by its ability to decrease force swim stress, induced immobility time in rats as well as restoring the biogenic amines to normal level that were altered by the swim induced stress in whole rat brain. Therefore, PF can be a potential candidate for treatment of depression as well as a potent antidepressant. However, further studies are required to substantiate the same
Isolation of Bacillus spp. Bacteria from Soil for Production of Cellulase
Full text linkCellualse is one of the most important enzymes used in textile, detergent, paper, food and feed industries. Therefore, a study was undertaken to isolate Bacillus bacteria having the potential to produce cellulase from soil samples. 24 soil samples were analyzed and 54 presumptive Bacillus isolates were isolated after heating the soil samples at 80°C for 10 min. Among them 45 isolates showed enzyme activity ranging from 0.003 to 0.17 U/ml in test tubes containing 5 ml medium composed of (g/L) glucose 0.5 gm, peptone 0.75 gm, FeSO4 0.01 gm, KH2PO4 0.5 gm, and MgSO4 0.5 gm at 120 rpm, 37° C and pH 7. Among them 1RW, 2WS, 3YR, 4WT, 6 RR, and 9SS showed 0.17, 0.15, 0.14, 0.15, 0.147 and 0.14U/ml enzyme activities, respectively. Production of cellulase by these isolates was further scaled up to shake culture containing 50 ml medium similar to that used in test tube culture. Among the isolates 1 RW showed the maximum activity. This 1 RW was identified by API kit and showed that 59 % belongs to Bacillus licheniformis strain (51% confirmation) or Bacillus subtilis (31% confirmation). Further gene analysis is required to confirm the species. The genetic improvement study will make the isolate a good source of cellulase
Comparative Study of Growth Statistics of Two Species of Paulownia and Optimization of Rooting Methods
Full text linkPaulownia is a fast-growing woody tree, native to the forests of China. It belongs to the family Scrophulariaceae and is mainly used as a source of wood for furniture and musical instruments. Due to its fast-growing nature and high-quality of wood, there has been growing interest in cultivation and research of Paulownia in Nepal. Growth comparison was performed by measuring shoot length in in vitro condition. Among two species of Paulownia - Paulownia tomentosa (Thunb.) Steud and Paulownia fortuneii (Seem.) Hemsl., the growth rate of P. tomentosa was found to be 0.355 cm/week while that of P. fortuneii was found to be 0.637 cm/week in in-vitro conditions in MS medium supplemented with 0.1 mg/l NAA and 1mg/l BAP. Optimization of rooting methods was also performed, in which, sand rooting was found to be easier and more effective than in-vitro rooting. Dipping the plantlets in 1 mg/l of NAA was found to produce longer and denser roots than lower or higher concentrations during sand rooting
Polyphenols: Nature\u27s Gift as dietary phytoconstituents against different human ailments
Full text linkRecently, researches and scientists are showing a lot of interests in bioactive compounds of plants and its products as these constituents are of high valued. Polyphenols are phytochemical constituents which are the integral components in plants and their products that are associated with defensive mechanism against infections and various oxidative stress by free radicals. Green tea, fruits, vegetables, cereals and red wines are rich sources of polyphenolic constituents which attributes prevention from infections and diseases because of its antioxidant properties, anti-diabetic properties, and radical scavenging properties. Oxidative stress which is the primary reason for different ailments in humans is due to the free radicals that are present even during the normal health condition. Polyphenolic acids like cinnamic acid, romarinic acid, stilbenes like resveratrol, flavonoids like catechin, taxifolin, quercetin, and lignans like sesamin, pinoresinol, podophyllotoxin etc. are found to be effective against wide range of human diseases like oxidative stress, cardiovascular disorder, neurodegenerative diseases, aging, and cancer. These phytoconstituents prevent the diseases and provide relieving sensation via different mechanisms. Here, the study shows the importance of polyphenols with respect to the relevance of human health. As there are the promising applications of various bioactive constituents in a wide range of disease, further research should be encouraged on the mechanism of action and bioavailability of polyphenols
Trichoderma species as Biocontrol Agent against Soil Borne Fungal Pathogens
Full text linkSoil borne pathogenic fungi are of major concern in agriculture which significantly decreases the plant yield. Chemically controlled plant imposes environmental threats potentially dangerous to humans as well as other animals. Thus, application of biological methods in plant disease control is more effective alternative technique. This study was carried out to isolate Trichoderma species from soil sample and to assess its in vitro biocontrol efficacy against fungal pathogens viz. Sclerotium rolfsii, Sclerotionia sclerotiorum, Fusarium solani and Rhizoctonia solani. Biocontrol efficacy testing of isolates against different fungal pathogens was performed by dual culture technique.In this study, 5 different Trichoderma species were isolated from 26 various soil samples and were tested against four fungal soil-borne pathogens. Inhibition percentage of radial growth of Sclerotium rolfsii by three of the Trichoderma isolates was found to be 100%; about 62% and 68% of maximum inhibition was observed against Rhizoctonia solani and Fusarium solani respectively whereas Sclerotionia sclerotiorum was inhibited maximum up to 23%. This in vitro study revealed that although Trichoderma species plays an important role in controlling all type of soil borne fungal plant pathogens, however, isolates as biocontrol agent against Sclerotium rolfsii was found to be more efficient in comparison to other pathogens.Nepal Journal of Biotechnology. Dec. 2017 Vol. 5, No. 1: 39-4
Apoptosis: Implications in Viral and Mycobacterium tuberculosis infections
Full text linkApoptosis is a form of programmed cell death leading to genetically controlled self-destruction of cells. It is essential in the development, maintenance, and regulation of cells during physiological as well as pathological conditions. Deregulation of apoptotic mechanisms is associated with various pathological diseases including cancer, autoimmune disorders, viral and bacterial infections. Virus and Mycobacterium tuberculosis elicit host cell apoptosis as a part of host immune defense or pathogen dissemination. They inhibit both extrinsic and intrinsic pathways of apoptotic mechanisms facilitating pathogen survival and escape from host immune defense.Nepal Journal of Biotechnology. Dec. 2017 Vol. 5, No. 1: 46- 5
Analysis of Phytoconstituents and Biological Activities of Different Parts of Mahonia nepalensis and Berberis aristata
Full text linkThe phytochemicals and biological activities of extracts from leaves and stem of Mahonia nepalensis and Berberis aristata were carried out. Phytochemical screening showed the presence of alkaloids, steroids, polyphenols, quinones, glycoside, flavonoid, terpenoid and cardiac glycoside in the hexane, ethyl acetate and methanol extracts of leaf and stem of these two plants. The column chromatography of methanol extract of stem of Mahonia nepalensis resulted in isolation of four pure compounds MN1, MN2, MN3 and MN4. Out of four isolated compounds, two were identified as MN1:b- sitosterol and MN2: Berberine by comparison of melting point, Co-TLC, IR and UV spectra of authentic sample. Potent pharmacological activity of Mahonia nepalensis and Berberis aristata were revealed from antimicrobial activity and brine shrimp bioassay. Methanol extracts of stem of Mahonia nepalensis and Berberis aristata showed significant zone of inhibition of 18 mm and 21 mm respectively against the Staphylococcus aureus. Methanol extract of Berberis aristata were comparatively little stronger against Staphylococcus aureus than methanol extract of Mahonia nepalensis. LC50 values (μg/ml) of methanol extracts of stem of Berberis aristata and Mahonia nepalensis were found to be 8.058x10-4 and 8.3 whereas methanol extracts of leaf of Mahonia nepalensis and Berberis aristata were 389.04 and 1303.166 respectively.Nepal Journal of Biotechnology. Dec . 2 0 1 7 Vol. 5, No. 1: 5-1